(a) Field of the Invention
The present invention relates to a method for preparing a hybrid supported metallocene catalyst. More specifically, the present invention relates to a method for preparing a hybrid supported metallocene catalyst that can be used in the preparation of an olefinic polymer.
This application is a National Stage Application of International Application No. PCT/KR2014/009680, filed Oct. 15, 2014, and claims the benefit of Korean Patent Application No. 10-2014-0138347, filed Oct. 14, 2014, and Korean Patent Application No. 10-2013-0124517, filed Oct. 18, 2013, the contents of which are incorporated herein by reference in their entirety for all purposes as if fully set forth below.
(b) Description of the Related Art
Olefin polymerization catalyst systems can be classified into Ziegler-Natta and metallocene catalyst systems, and these highly active catalyst systems have been developed in compliance with their characteristics. Ziegler-Natta catalyst has been widely applied to existing commercial processes since it was developed in the 1950's. However, since the Ziegler-Natta catalyst is a multi-active site catalyst in which a plurality of active sites are mixed, it has a feature that molecular weight distribution is broad. Also, since compositional distribution of comonomers is not uniform, there is a problem that it has a limitation to secure the desired physical properties.
Meanwhile, the metallocence catalyst includes a main catalyst whose main component is a transition metal compound, and an organometallic compound cocatalyst whose main component is aluminium. Such a catalyst is a single-site catalyst which is a homogeneous complex catalyst, and offers a polymer having a narrow molecular weight distribution and an uniform composition distribution of comonomers, depending on the single site characteristics. The stereoregularity, copolymerizing properties, molecular weight, crystallinity and the like of the resulting polymer can be controlled by changing the ligand structure of the catalyst and the polymerization condition.
U.S. Pat. No. 5,032,562 describes a method for preparing a polymerization catalyst by supporting two different transition metal catalysts on one supported catalyst. This patent relates to a method for preparing polymers having a bimodal distribution by supporting a Ti-based Ziegler-Natta catalyst which produces a high molecular weight polymer and a Zr-based metallocene catalyst which produces a low molecular weight polymer on one support, and has disadvantages in that the supporting procedure is complicated and the morphology of polymers is deteriorated due to a cocatalyst.
U.S. Pat. No. 5,525,678 discloses a process for using a catalyst system for olefin polymerization in which a metallocene compound and a non-metallocene compound can be simultaneously supported on a support to simultaneously polymerize a high molecular weight polymer and a low molecular weight polymer. However, this patent has disadvantages in that the metallocene compound and the non-metallocene compound must be separately supported and the support must be pre-treated with various compounds for the supporting reaction.
U.S. Pat. No. 5,914,289 discloses a method of controlling the molecular weight and the molecular weight distribution of polymers using metallocene catalysts which are respectively supported on supports. However, a large amount of solvent and a long period of time are required to prepare the supported catalysts, and the process of supporting metallocene catalysts on the respective support is troublesome.
Korean Patent Application No. 2003-12308 discloses a method of controlling the molecular weight distribution of polymers by polymerizing while changing a combination of catalysts in a reactor by supporting a bi-nuclear metallocnene catalyst and a mononuclear metallocene catalyst on a support with an activator. However, this method has a limitation to simultaneously secure the properties of the respective catalysts. In addition, there is a disadvantage that a metallocene catalyst portion is departed from a supported catalyst to cause fouling in the reactor.
Therefore, in order to solve the above-mentioned disadvantages, there is a need to develop a method for preparing olefinic polymers with the desired physical properties by easily preparing a supported hybrid metallocene catalyst having an excellent activity.